Movable deck pneumatic coal cleaner



July 4, 195o C. v. ORE 2,513,960

MOVABLE DECK PNEUMATIC COAL CLEANER Filed Feb. 13, 1947 2 Sheets-Sheet 1mama .hay '4, raso MOVABLE DECK PNEUMATIC COAL CLEANER Carl V. Ore,Harvey, Ill., assigner to Roberts and Schaefer Company, Chicago, Ill., acorporation of Illinois Application February 13, 1947, Serial No.728,224

l 4 Claims.

This invention relates to the separating or classii'ying ofheterogeneously intermixed materials consisting of particles ofdifferent specific gravities and/or sizes, and is particularly concernedwith improvements in a movable deck pneumatic coal cleaner for useprimarily with raw coal of relatively small particle size.l

The term coal cleaner is applied to apparatus such, for example, asdescribed in U. S. Patents Nos. 2,245,942 and Re. 21,682. The apparatusdisclosed in these patents comprises means forming an inclinedtrough-like passage provided with a perforated air-pervious deck platedisposed on top of a resistance pack containing marbles or the like, andmeans for directing air impulses into and through the resistance packfor escape upwardly through the perforations in the deck plate. The rawcoal is fed to the deck plate at the elevated end thereof, moving alongits inclined surface, and is subjected to the action of the air impulseswhich eilect stratification of its particles in accordance with theirspecific gravities. Coal, which is the lightest component of the rawfeed, orients itself on top of the material bed and heavier particles,constituting refuse, stratify underneath the coal. The variousstratified products are drawn olf for removal to their respectivedischarge points.

The principal object of the invention is to provide an airflow separatoror cleaner of the general class described above for treating raw coal ofsmall particle size varying, for example, from about three-eighths of aninch down to and including nely pulverized and comminuted dustlikeparticles, and for obtaining clean coal of a high degree of purity suchas is required in metallurgical coal and in pulverized coal for numerousindustrial operations including the operation of marine and locomotiveboilers,A cementburning, central heating plant operation and the like.

This object is realized by the provision of a structure having (1) anelastically suspended longitudinally resiliently Ibalanced trough-likeinclined material deck for receiving the raw mate- 'rial, the deckcomprising a plurality of longitudinally serially related deck sections,each section including a perforated air-pervious deck plate and aresistance pack, the successive deck sections beingseparated bydownwardly directed intermediate discharge passages for the removal fromthe material stream of successively separated relatively coarse heavymaterial particles; (2) means forming underneath the material deck 'aplurality of cells, one for each deck section,

and means for injecting into each cell air impulses of controlledmagnitude for adjusted upward escape through the associated resistancepack and perforated deck plate into the raw material thereon to impartcontrolled fluid mobility and buoyancy to such material; (3) means forreciprocating, vibrating or oscillating the material deck with all itsdeck sections at a relatively high frequency and relatively smallamplitude for the two-fold purpose of imparting mechanical mobility tothe material flowing over the various deck sections and to cause iinelydivided particles of intermediate specic gravities to move for dischargecontinuously downwardly through the deck plate and through theunderlying resistance pack of each deck section in counter-current tothe air impulses injected into the corresponding deck section; and (4)means common to all deck sections for receiving and removing the smallparticles of intermediate gravities which are continuously dischargedtherefrom in countercurrent to the air impulses injected thereinto.

Details of the various objects and features, including those mentionedabove, will appear from the description of the accompanying drawings, inwhich Fig. 1 shows a more or less diagrammatic elevational side view ofan embodiment of an airiiow separator or cleaner made in accordance withthe invention, with parts broken away to show interior structures;

Fig. 2 is a section, on an enlarged scale, through the new separatortaken approximately along lines 2 2 of Fig. 1; and

Fig. 3 illustrates, on an enlarged scale, -the means for longitudinallyresiliently balancing the material deck, as seen when looking in thedirection of the arrows along lines 3--3 of Fig. 1.

Like parts are numbered alike throughout the drawings. Known details andelements will be referred to only to the extent required for conveyingan understanding of the structure and operation of the invention.

Referring now to the drawings, the new separator comprises a frameworkincluding suitably positioned structural upright members ll, l2 and I3,I4 disposed on either side of the machine substantially at the oppositeends thereof. The uprights I 2 and I3 on either side are joined bysuitable sheet members forming the side Walls 14 and l5 which extendthroughout the lower part of the machine. Vertically extending sheetmembers join the uprights I3, I4 on either side in the rear and similarsheet members extend forwardly from the uprights H to the left as seenin Fig. 1. The forward end of the machine may be closed by a suitableplate or the like. Secured to the top of the uprights I2 and I3on'either side and extending therebetween in longitudinal direction arethe generally U-shaped girders I5 and I6, respectively, (see also Fig.2). Secured to the girders I5 and I6 are downwardly extending andoutwardly aring shields |50, and IBa, respectively.

Each girder I5 and I6 carries a number oi longitudinally spaced bracketssu-ch as I1, I8, I9, and suitably attached to each of these brackets isa downwardly depending resilient member, e. g., a composite or laminatedleaf spring. The leaf springs secured to and depending from the bracketsI I8, I 9 on the girder I5 are marked 20, 2I, 22, respectively. The topgirder I6 extending on the other side, in back of the girder I E, asseen in Fig. 1, carries in a similar manner brackets corresponding toI7, I8 and I9, one such bracket being indicated in Fig. 2 at 23, andleaf springs corresponding to the springs .22, 2l and 22 are secured tosuch brackets, the leaf spring corresponding to spring 2| beingindicated in Fig. 2 by numeral 26. There are thus three pairs of leafsprings 2t, 2I24 and 22, which extend downwardly from the top girders I5and I5.

The lower ends of the three pairs of leaf springs are secured tobrackets which project laterally outwardly from longitudinallyextending, generally U-shaped structural members 25 and 26 disposedslightly above and vertically spaced from the side walls i4 and 15,respectively. The4 structure is apparent from Fig. 2, showing the lowerends of the pairs of leaf springs 2l and 24 associated with the brackets2l--2B, respectively, which extend laterally outwardly from the members25-20. The lower ends of the pairs of leaf springs and 22 are securedsimilarly to brackets extending laterally from the members and 25. Thelongitudinally extending structural members 25 and 26 are thuselastically suspended from the longitudinally extending top girders I5and I6 of the machine and are transversely spaced as is particularlyapparent from Fig. 2. These members form part of the material deck andcarry the serially related deck sections. Upwardly extending andoutwardly flaring shields 25a and 26a are secured to the structuralmembers 25 and 26, respectively, forming with the deck sections alongitudinally extending trough-like structure which is inclined at anangle of about 8 to 15 degrees.

At the rear end of the material deck is disposed a generally U-shapedstructural member 29 which extends transversely across the rear ends ofthe longitudinally extending resiliently suspended deck members 25 and26. From the member 20 extends in rearward direction a connectingmember, e. g., an I-beam 30. This connecting member is associated withsuitable means for imparting vibrations thereto which are transmitted tothe material deck, including all the deck sections disposed between thestructural members 2'5 and 2S, for example, with a vibrator 3 I. Thisvibrator may be of the rotary type known as ,Eureka Buhler Drive,manufactured by S. Howes Co., Inc., Silver` Creek, N. Y., comprising twodisk-like masses whose axes of rotation are radially oiset such asillustrated by the Shaler Patents 1,999,213 and 2,059,784. These massesare rotated in common and produce thrusts which affect the connectingbeam 30, thereby vibrating, reciprocating or oscillating the materialdeck. The vibrator is operated through the medium of a belt drive,

from a motor 32 mounted on a shelf 33 secured between the rearmost pairof upright members I4. Other suitable means for reciprocating, vibratingor oscillating the material deck may, of course, be used.

The frequency of the vibrations or oscillations imparted to the deck maybe from about 800 to 1400 per minute; the amplitude may be approximatelylg", that is, 115 in either direction from the normal position of thematerial deck. It will be seen, therefore, that the amplitude of thevibrations is relatively small, while the frequency is relatively high.

The suspended inclined material deck with its various deck sections israther heavy, and the structure would normally tend to position itselfby gravity in a forward direction; that is to say, it would tend to sagtoward the left as seen in Fig. 1. Vibrations applied directly to thefreely suspended structure would be distorted by the inertia of themasses in the presence of such sagging, In order to counteract thesagging and to control the vibrations, I have provided means forresiliently balancing the structure in longitudinal direction. Thisbalancing means is indicated in dotted lines at the rear end of themachine, as seen in Fig. 1, and is there generally indicated bythenumeral 35. It is shown on a larger scale in Fig. 3.

The balancing structure comprises a pair of transversely extendingsupports 36 and 3l which are attached to the pairs of uprights I3 and I4in the front and in the back of the machine, respectively. Mounted onthe members 36-3i and connecting such members is a shaft 38. It will benoted that the ends of the shaft are secured in bushings 39 and 40, bymeans of pairs of nuts 4I, d2 and 43, 44, respectively, and that theshaft can therefore be positioned with respect to the transverse members35, 3i as may be desired. The shaft carries a floating bushingassociated with a bracket member 46 which extends upwardly as shown inFig; l and is secured to the connecting I-beam 32 projecting rearwardly.from the transverse member 20 at the rear end of the suspended deck andcarrying the vibrator or oscillator 3l. Also secured on the shaft 38 ofthe balancing structure are a pair of flanged bushings 4l and 48,respectively, and between these bushings and the member le are disposedsprings 49 and 50. The spring l@ extends between the bushing 4l andmember 46, and the spring 50 extends between the bushing 48 and member46. The position of the bushings Il and 83 on the shaft 33 may beadjusted as desired, by the nuts 5i and 52, for the purpose of adjustingthe tension or pressure of the springs 49, against the member t5.

The structure thus permits adjustment of the spring pressure against themember d6 (which is connected with the connecting beam 30 projectingrearwardly from the elastically suspended material deck and carrying thevibrator 3i) and also permits resilient adjustment of the position ofthe member 46 relative to the supports 36-3L and therewith adjustment ofthe connecting beam S0 and the material deck in a desired normalposition. The operation of the vibrator ti vibrates the material deck,and the vibrations are controlled by the springs 45, 50 pressing againstthe member 46 carried on the floating bushing t5.

The adjustment counteracts the forward sagging of the material deck,which would other- Wise take place due to the incline at which it isdisposed... The vibrations or oscillations imparted by the vibrator 3|to the connecting beam Il and thence to the forwardly extending materialdeck are damped and cushioned. Forces set up during the vibration, dueto inertia, are eectively counteracted. 'I'he amplitude of thevibrations, as noted before, may be 11u" to either side of a mediancenter line which may be drawn through the member 46, as shown in Fig.3, after completing the adjustment. 'I'he amplitude is, of course, not afixed quantity and may be chosen as desired, being given as an example.

There are four deck sections provided in the structure shown in thedrawings. The rearmost or first deck section is indicated in Fig. 1 bythe numeral 60. This deck section terminates at its forward end in adownwardly extending intermediate discharge passage indicated in Fig. 1by the numeral 6|, which separates it from the second deck section 62. Asimilar downwardly extending intermediate discharge passage 63 separatesthe forward end of the deck section 62 from the rear end of the thirddeck section, the forward end of which terminates in the downwardlyextending similar discharge passage l64. 'I'he fourth or last decksection terminates iin the discharge passage 65 near the forward end ofthe machine. Numeral 66 indicates the discharge for the clean coal.

A weir such as 80 is shown in Fig. 1 associated with the rear end of thedeck sectio'n 62. This w eir is a transversely extending plate which isvertically adjustable so as to provide a banking effect with respect tothe raw material stream owing from the deck section 60 over and onto thedeck section 62. Similar weirs may be associated with each of thedischarge passages 63. 64 and 65.

Each deck section comprises a perforated airpervious deck plate on topof a resistance bed containing suitable members, for example, claymembers or glass marbles of a desired size, say 1/4" to 11e" indiameter. The structure of the deck sections, including the associatedperforated deck plates and marble packs. will be apparent fromconsulting the previously mentioned Patents 2,245,942 and Re. 21,682.

The perforated deck plates may be made of suitable material, e. g.,brass, but are preferably made of stainless steel. The size of the holesin the deck plates is chosen so as to provide for a maximum open area ofabout 22% to about 30%. For example, there may be 108 holes per squareinch, each hole of a diameter of .05" resulting in an open area of 23%,or 400 holesv per square inch, each hole of a diameter of .027" alsoresulting in an open area of 23%; or there may be 225 holes per squareinch, each hole of a diameter of .04" resulting in an open area of 28%.

Underneath each deck section are disposed transversely extending valveslides such as 61-68 (shown in Fig. 1 in connection with the first decksection 60) which are movably mounted between guide members such as 69.Each valve slide is provided with openings coacting with openings in thebottom plate of the associated deck section and is movable or slidabletransversely by a suitable means, for example, an adjusting screw,extending to the outside. The arrangement is apparent from Fig. 2,showing part of the deck section 62. Underneath the bottom plate 55 isindicated the valve slide 56 which is operable by means of an outwardlyprojecting screw 51. Each deck section is provided with such valveslides for the purpose of regulating the air supply into and through itsmarble pack for escape through 75 the perforations in its associateddeck plate.

Further details of the structure and operation of the valve slides maybe had from Patent No. 2,374,865.

Each downwardly extending intermediate discharge passage 6|, 63, 64 and65 separating the various deck sections terminates in a dischargemechanism comprising a transversely extending casing such as 13containing an arcuate tray 10 and an oscillating/scraper 1| as well as arotatable transversely disposed screw 12. The casing containing thesedischarge elements extends transversely within the lower part of themachine underneath the associated intermediate discharge passage, thatAis, within the space dened .by the side walls 14 and 16 (see also Fig.2). wardly extending passage directed into the discharge mechanism areconnected with the associated casing, such as 13, by suitabletransversely extending flexible bellows-like sealing members, asindicated in Fig. 1, so as to. prevent the escape of air into thedischarge mechanism. They discharge casing 13a shown in Fig. 2correponds to the casing 13 of Fig. l, and contains the dischargemechanism for the intermediate discharg`e passage 63 including the screw12a which .corresponds to screw 12 indicated in Fig. 1. The transversebellows-like seal |13 extends from the casing 13a and connects with theplate forming part of the discharge passage 63 to prevent the escape ofair into the casing 13a.

flach discharge mechanism is associated with an end plate at the frontand a similar end plate in the back, and these plates are mounted on theside walls 14'and 15, respectively. The end plates I2 and 82a are thusassociated with the discharge mechanism for the intermediate dischargepassage 63 (see Figs. 1 and 2); the front end'plate 8| coacts with asimilar end plate on the side wall 15'of the machine in connection withthe intermediate discharge 64; and similar front and back end plates areprovided for the discharge mechanism associated with the intermediatedischarge passage 6|. These end plates carrycertain operating parts.

The discharge mechanisms are actuated from an eccenter 85 operated by amotor associated with a suitable speed reducer generally indicated inFig. 1 at 86. An arm 81 extends from the eccenter 85 into pivotalengagement with a connecting member 88 which in turn is pivotallyconnected by means of a rod 89 with a connecting member 90, the latterbeing connectedby a rod 9| with a connecting member 92lto which ispivoted the rod s3, and the forward end of the latter is pivotallymounted on the arm 94. When the eccenter 85 is actuated, it reciprocatesthe connecting rod 81 and therewith the gang of connecting rods 89, 9|and'93, oscillating in this 7 to oscillate the scraper such as 1| forthe purpose of feeding material to the discharge screw such as 12. Thearm |08 is similarly keyed to the shaft ||0 (Fig. 2) to oscillate thescraper associated with the discharge mechanism for the intermediatedischarge 63 so as to feed separated ma- The transverse plates formingthe down-` terial onto the screw 12a. The connecting rods |02, |03, |04and |05 are adjustable on their asscciated oscillating arms 94, 95, 96and 91, respectively, so as to adjust the stroke of the respectiveoscillating scrapers actuated by these rods.

The discharge screws move the discharged material laterally at thebottom of the associated casings for discharge into downwardly directedchutes. Thus the discharge screw l2 within the casing '|3 moves thematerial received from the intermediate discharge 6I into the chute IIB;the screw 12a (Fig. 2) within the casing `|3a moves the materialreceived from the discharge 63 into the chute I6; and chute I I1receives in a similar manner the material from the intermediatedischarge passage 64.- The discharge mechanism associated with thedischarge passage B5 at the forward end of the machine dischargesdirectly into the chute I I8.

The discharge screws associated with the various discharge mechanismsare operated by suitable drives, e. g., by chain and sprocket drivessuch as indicated in Fig. 2 at |20. f

Further details of the discharge mechanisms and their operation may behad from Patent No. 2,334,337.

At the bottom of the machine defined by a suitable bottom plate I2I(Fig. 2) are disposed three rotatably mounted pairs of screws, each pairbeing carried on a common shaft. The three shafts are indicated in Fig.2 by the numerals |22, |23 and |24. The pair of screws associated withthe shaft |24 are indicated by numerals |28 and |29.

\ left feed, respectively, to transport material accumulating at thebottom ofthe machine inwardly from its extreme ends toward the middlefor discharge into the chute |30. In this chute is disposed an air sealcomprising a star wheel I3! to prevent escape of air thereinto. The starwheel is operated by a suitable drive, for example, a chain and sprocketdrive |32, indicated in Fig. 2.

Extending downwardly from each of the casings containing the dischargemechanisms associated with the intermediate discharge passages 0 63 andSt, and secured to the respective casing, is a valve plate such asindicated at M0 in connection with the casing 'i3 (Fig. 1) provided forthe discharge mechanism which receives material from the passage 6|, orvalve plate iii! (Fig. 2) associated with the discharge casing l3a whichreceives material from the passage 63. The valve plate extends in eachcase transversely across cated at |02, M3, Mit, respectively, thesevalve i Each valve plate is provided with valve plate at |45 and Hit,which project downwardly into the spaces between the screws carried onthe shafts I 22|23 and |28| 24, respectively. Each of the extensions|45, |46 is likewise provided with an opening or openings, and the valveslide |44 carries extensions corresponding to the extensions |45, |46.Similar valve means carrying a valve plate and associated valve slidesis also connected with the discharge casing which receives material fromthe intermediatedischarge passage 64.

The chamber extending between side walls 'I6-l5 underneath the variousdeck sections is in this manner divided into cells, one for each decksection, and each cell is provided with means for regulating the airsupply that is to be admitted into it for use in its associated decksection.

The air supply may be from any suitable source by way of the duct |50(Fig. 1) which is provided with a flutter valve |52 operating betweenshields |62, |63. The air pressure is relatively low and may vary fromabout 1.25 WG to about 2.00 WG. The utter valve |52 is rotated atdesired R. P. M. by a suitable drive, for example, by a chain andsprocket drive, from the motor and speed reducer 06. Air impulses ofrelatively low pressure are thus suppliedinto the space or cell belowthe deck section 60, and the amount of air which is admitted into thisdeck section is regulated by the valves such as 68 and 61 disposeddirectly underneath its resistance pack.

The admission of air into the second cell underneath the second decksection 62 is regulated by the valves associated with the valve plate|40 depending from the casing 13. The air which is admitted for use inthe deck section 62 is regulated by the valve slides underneath itsresistance pack.

Air is similarly admitted into the third and fourth cells underneath thecorresponding deck sections by way of the valve plates I4| dependingfrom the casing 13a (Fig. 2) and from the casing associated with thedischarge passage 64, respectively.

Vertically extending valve openings may be provided in the partitionvalve plates such as |40, |4| instead of the rows of openings described,for valve coaction with similarly formed valve slides or sliding plates.

The raw material is supplied through a hopper |65 (Fig. 1) and dropsonto an inclined surface formed by the transversely extending plateI6I.y This plate deflnes the bottom of a feed chamber in which isdisposed an oscillating feed mechanism operable by the oscillating arm|61. feed mechanism may be similar to the discharge feed mechanisms usedin connection with the various discharge passages tl, S3 and 64, anddetails of it may be had by consulting Patent No. 2,334,337. Shieldssuch as |68 extend on either side forwardly from the feed chamber toguide the raw material into the trough of the vibrating material deck.

The oscillating or vibrating deck comprising the various deck sectionsas described is connected with the lower part of the machine by means ofilexible bellows-like sealing members |'|I, |12, the bellows il!connecting the deck with the side wall M and the bellows |112 connectingwith the side wall l5. Transverse bellows members of similar structureare provided at the forward and at the rear ends of the oscillatingdeck. The deck with its various deck sections is thus sealed against theescape of air except through the perorated deck plates and is movable onits suspension springs in response to the actuation of the vibrator.

The sxTids wit-:sa and Isam extending from the top girders I and I6 vandfrom the suspended deck members and 25, respectively, may be connectedby a suitable material such as canvas members so as to seal and closethe top part of the machine, above the vibrating deck. to the outside.

A dust hood |80, shown in Fig. 1, extends upwardly from the machine andterminates in a suitable exhaust duct for drawing dustvladen air of! forcleaning and recirculation back to the intake |50.

The-operation of the machine may now be brieiiy summarized as follows:

The raw coal is supplied to the hopper |65. The operation is started byswitching on the motor 86 provided with a speed reducer, thusrotating'the eccenterf85 and thereby oscillating the arms ill-51 whicheifect the oscillation of the discharge Scrapers such as 1| ofthedischarge .mechanisms associated with the various intermediatedischarge passages 6|, 63, 64 and 65. The arm |61 is at the same timeoscillated for the purpose of actuating the mechanism for` feeding theraw material onto the first deck section 60. Air under pressure issupplied to the duct |50, and the flutter valve |52 is rotated at apredetermined R. P. M. to admit air to the machine in the form ofimpulses. The operation of the vibrator 3| is started by switching onthe motor 32. The discharge screws associated with the variousintermediate discharges are actuated l of the raw material are thusdischarged through by the corresponding chain and sprocket drives suchas |20 in Fig. 2'.

The air admitted into the cell underneath the first deck section 60flows upwardly through the resistance pack of this section and throughthe perforated deck plate in accordance with the setting of the slidevalves such as 60 and 61. The amount of air to be admitted to the seconddeck section 62 is regulated yby suitably adjusting the slide valvesassociated with the valve plate depending from the discharge casing `13.The air admitted to the third and fourth deck sections is likewiseadjusted by the slide valves associated with the discharge casings inback of the mounting plates 82 and 8|, respectively. Each of the decksections is provided with slide valves such as 68 and 61 for furtherregulating the air supply directed through the corresponding resistancepack for` upward escape through the associated perforated deck plate inaccordance with the needs of the material bed flowing over each `decksection. I

The raw material flows onto the rst deck section and is subjected to theactin of the air impulses as well as to the action of the vibrationseffected by the vibrator 3|. The magnitude of the air impulses isadjusted to the needs of the raw material bed forming on this decksection. The material immediately orients itself in stratified layers asit flows along the first deck section, and upon arriving at the rsttakeoff or intermediate discharge passage 6|, the heaviest and largestcomponentsA are positioned at the bottom of the material bed and dropdown onto the discharge tray 10 from which they are scraped by thescraper 1| onto the screw 12 which feeds the discharged particles intothe chute or duct ||5. The Weir 00 and similar weirs associated with thesuccessive intermediate discharge passages 63, 64, are adjusted todesirable heights so as to provide proper banking oi' the materialstream at the corresponding discharge points. The heaviest and largestcomponents the passage 6| and removed through the chute ||5.

The remaining material continues to flow onto and along the second decksection 62 on which it is subjected, in the presence of vibrations, toair impulses of a magnitude adjusted to its needs, and the heaviest andlargest components of the material, which'stratify under the action ofsuch impulses and vibration at the bottom. drop downwardly into andthrough the intermediate discharge passage 63 for removal into chute ||6by mea-ns of the discharge mechanism contained in the discharge` casing13a (Fig. 2) which is identical with the mechanism associated with thedischarge passage 6|, as shown in full lines in Fig. 1.

The material remaining after removal of heavy and relatively largeparticles at the intermediate discharges 6| and 63, as described,continues to now along the third and finally over and along the fourthdeck section, at the end of each of which the heaviest and largestcomponents are discharged through the associated intermediate dischargepassages 64 and 65, respectively, for removal through the ducts orchutes ||1 and i8, respectively.

The clean coal flows over the inclined end section 66 of the vibratingdeck for discharge through the chute |10.

Finely divided matter contained in the material as it flows along thevarious deck sections, consisting of particles of intermediate gravitiesand of maximum sizes corresponding approximately to the size of theopenings in the various deck plates, works continuously andprogressively downwardly through such openings and through thecorresponding resistance packs, in countercurrent to the upwardlydirected air impulses, leaving the resistance packs through the bottomopenings associated with the valve slides underneath each deck section.These particles drop downwardly to the bottom of the machine where theyaccumulate along the bottom plate |2| At a certain point of theoperation the screws on the shafts |22, |23 and |24 on top of the bottomplate |2| are started by their respective drives such as |21, and thestar wheel |3| is rotated by means of the chain and sprocket drive |32.The fine material of intermediate gravities that has accumulated willaccordingly be moved from either end of the machine toward the middleand will drop onto the star wheel |3| which discharges the material in acontrolled manner downwardly into the chute |30, and at the same timeacts as an air vseal to prevent the escape of air. The maximum size ofthe particles thus discharged is determined by choosing holes or.corresponding size to be provided in the various deck plates.

The progressive and continuous discharge of the finely divided particlesof intermediate gravities throughout the extent of each deck section, incounter-current to the air impulses, as described in the foregoingparagraph, is considered an -important feature4 of the presentinvention. As intimated initially, thisl feature effects automaticcleaning of the resistance packs, permits more eicient utilization ofthe air' at reduced pressures, accelerates stratification, therebyincreasing the ton/hour capacity of the separator at reduced energyinput, and thus permits the efficient treatment of raw coal ofrelatively small particle size without recourse to hydraulic separation,delivering clean coal of a high degree of purity.

'I'he separated products, which are discharged passages 6I, 62 and 63into the chutes I I5, I I6 and H1, respectively, consist predominantlyof heavy particles constituting refuse. The nes, which are dischargedfrom all of the deck sections in counter-now to the air impulsesdropping to the bottom of the machine for removal into the chute 130,have likewise been found to consist predominantly of heavy particlesconstituting refuse. The material entering the intermediate dischargepassage 65 at the forward end of the fourth deck section for removalthrough the chute i I8 will, however, usually contain valuable particleswhich are recovered by screening, the underflow being predominantlyrefuse and the overflow from the screen being either predominantly coal,which is mixed with the coal drawn off at the inclined forward end 66 ofthe deck, ora true middlings product which may be recirculated. It isunderstood, of course, that conditions may vary and, if it is found thatone or the other intermediate product contains valuable material, suchproduct may be screened and/or re-circulated as desired or necessary, torecover its valuable constituents.

The new apparatus and process has been described in connection with theseparation or cleaning of coal for which it has been designed. Some orall of the new features may be used in related or different fields,including the beneciation of minerals and ores.

Changes may be made within the scope and spirit of the appended claimswhich define what is believed to be new and desired to have protected bvLetters Patent of the United States.

I claim:

1. In apparatus for separating raw co'al of relatively small particlesize having a longitudinally extending air-pervious material-receivingdeck disposed above a resistance pack which forms an operating unittherewith and having means for feeding ra-w coal onto said deck at oneend which forms the feed end thereof, relatively stationary supportsdisposed above said operating unit, resilient hanger means secured toand downwardly depending from said supports for suspending saidoperating unit at an incline with the feed end disposed at a higherlevel than the opposite end which forms the coal discharge end thereof,said incline being at an angle at which gravitational force willnormally tend to move said operating unit causing sagging thereofforwardly awayv from said means for feeding raw coal onto the feed endthereof, means forming an arm disposed at the feed end of said operatingunit and longitudinally rearwardly extending therefrom underneath saidmeans for feeding raw coal thereto, an unbalanced Weight vibrator solelysupported on said arm ai; the free end thereof, balancing means coactingwith said arm for longitudinally resiliently balancing said inclinedoperating unit in predetermined longitudinally adjusted position tocounteract said gravitational force and to position the feed end thereofin predetermined normal position relative to said raw coal feedingmeans, said balancing means comprising a pair of spaced relativelystationary supports, a shaft extending between said supports, a bushingdisposed on said shaft and floating thereon, means for relativelyrigidly connecting said bushing with said arm, spring means disposed onsaid shaft on either side of said bushing and means disposed on saidshaft for compressing each spring means against said bushing, and meansfor actuating said vibrator to vibrate said operating unitlongiextending air-pervious material-receiving decky disposed above aresistance pack which forms an operating unit therewith and having meansfor feeding raw coal onto said deck at one end which forms the feed endthereof, relatively stationary supports disposed above said operatingunit, resilient hanger means secured to and downwardly depending fromsaid supports for suspending said operating unit at an incline with thefeed end disposed at a higher level than the opposite end which formsthe coal discharge end thereof, said incline being at an angle at whichgravitational force will normally tend to move said operating unitcausing sagging thereof forwardly away from said means for feeding rawcoal onto the feed end thereof, means forming an arm disposed at thefeed end of said operating unit and longitudinally rearwardly extendingtherefrom under` one of said stationary supporting members, a

bushing disposed on said shaft about midway thereof and oating thereon,means for relatively rigidly connecting said bushing with said arm whichextends rearwardly from said operating unit underneath said means forfeeding raw coal thereto, spring means disposed on said shaft-on eitherside of said bushing, means disposed on said shaft for compressing eachspring means against said bushing, an unbalanced weight vibrator solelysupported by and secured lto said arm at the free end thereof, and meansfor actuating said vibrator t'o vibrate said operating unitlongitudinally for the two-fold purpose of imparting4 mechanicalmobility and buoyant fluidity to the material particles on said deck andto cause particles of intermediate specific gravities to move downwardlythrough said air-pervious deck plate and through said resistance packfor downward discharge therefrom whereby clogging of said resistancepack is prevented to maintain its air resistance characteristicssubstantially constant.

13 REFERENCES crrnn Nluggs The following references are of record in the21001356 111e o! this patent: 5 2,183,281 UNITED STA'I'ES PATENTS 52,374,865 Nuxzxberzq: Li Name A bDlaizelwg Y jqjflo Dfs': c: 3: m0332339 1,843,405 Raw Feb. 2. 1932 Name Y Date Friend Aug. 30, 1932 WoockMay 21, 1935 Ridley Dec. 12, 1939 Haworth May 1, 1945 FOREIGN PATENTSCountry Date France June 30, 1934

